Ground-plug for electrical switchboards.



No. 649,371. Patented May 8, I900. W. l. STOCKDON,

GBOUND PLUG FOR ELECTRICAL SWITCHBUABDS.

(Application filed Feb. 16, 1900.

(No Model.)

5 1';- i Q T AK F E- 29 I 4 c x a r A E 6' I I I I WITNESSES gj /NVENTOR Wilz yfi'zcfidon.

A TTOHNEYS W'ALLAOE IRVING STOOKDON, OF ORANGE, VIRGINIA.

GROUND-PLUG FOR ELECTRICAL SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 649,371, dated May 8,1900.

Application filed February 16, 1900. erial No. 5,548. (No model.)

To aZZ whom it may concern.- L

Be it known that LWALLAcn IRVING S'rooK- DON, of Orange, in the countyof Orange and State of Virginia, have invented a new and usefulImprovement in Ground Plugs for Electrical Switchboards, of which thefollowing is a specification.

Myinvention is an improvement in groundplugs for electricalswitchboards, and has for an object to provide a plug which whenproperly applied to a switchboard to ground the main circuit willoperate an audible signal independently of the main electrical circuitand will continue to sound as long as the plug is in place, so theoperator will be notified when through with a line and be sure to removethe plug,- the object being to insure the removal of the plug and soobviate the grounding of a wire except when desired.

The invention consists in certain novel eonstructions and combinationsof parts, as will be hereinafter described and claimed.

In the drawings, Figure 1 is a face View of a switchboard provided withmy improvements; and Fig. 2.is a detail view, partly in section, of theground-plug and its local circuit, battery, and sounder.

The switchboard A may be of any desired construction, that shown beingthe one now commonly used in telegraphing apparatus, and may beconnected with the main circuit and be adapted in any suitable way toreceive the ground-plugs B. These plugs 13, so far as grounding the lineis concerned, operate similarly to the plugs now in use, the novelfeature of such plugs being in the provision of a sounder operated by alocal circuit entirely independent of the main circuit and in the meanswhereby such result is accomplished. The purpose of grounding the lineis the usual one to cut out the station or stations on the side of thesending-station opposite that to which it is desired to send themessage, and the purpose of sounding the signal while the plug is in theboard is to constantly remind the operator of the grounding of the line,so he will not forget to remove the plug when he has concluded sendingthe message.

,In carrying out my invention I make the plug in sections insulated fromeach other and having such insulated sections forming erate when soinserted to ground the main circuit in the usual way and also to closethe local circuit, so its sounder will operate while the plug isretained in the switchboard. It is to be noted that the local circuit isnot operated by the current from the main circuit, but has its ownbattery or other equivalent source of electrical supply, so it will notin any way affect the operation of the main circuit.

In the construction shown the plug B is formed with the sections 0 0received at their butt-ends in the head D and spaced apart throughout.The butt-ends of the sections 0 O are insulated in any suitablemanner-it may be, by forming the spacing-block E and the head D ofsuitable insulating materialwhile the point ends a: and y of theplug-sections O and G are arranged to be pressed into contact When theplug is inserted in the switchboard, as will be understood from thedotted lines in Fig. 2, and thus close the local circuit F,wliichincludes the sections 0 and O and the battery G and sounder I l. It willthus be seen that the sections 0 0 form circuit-closing sections whichare nor mally insulated from each other and are arranged to be broughtinto electrical union or contact when the plug is in position in theswitchboard-socket.

Manifestly the battery and the sounder may be of any desiredconstruction.

In the operation when the plug is inserted in the switchboard to groundthe main circuit the endsoc and 1 of the sections 0 C will be pressedtogether, closing the local circuit, causing its sounder to operate. Theplug thus completes a local circuit of its own. It should be noted thatthe plug completes this local circuit through itself and forms acomplete signaling-circuit entirely independent of the mainline-circuit.

The butt-ends of the sections C O and their insulating-block E fit inthe head D and are suitably secured, it may be, by the screws I I claimas new, and desire to secure by Letters Patent, is-

1. A ground plug for electrical switchboards comprising the plug havingcircuitclosing sections normally insulated from each other and arrangedto form electrical union or contact when the plug is in position in theswitchboard socket, and a local circuit of which said sections form theterminals, such circuit containing a battery and sounder and beingarranged for operation independently of the current of the main circuitsubstantially as set forth.

2. A ground-plug substantially as described comprising the sectionsnormally separated at their point ends and arranged to be pressed intocontact at such end when in position in the switchboard socket,insulation for the butt-ends of said sections whereby they areelectrically detached, and a circuit containing a battery and a sounderof which circuit the plug-sections are the terminals substantially asset forth.

3. The ground-plug herein described comprising the sections normallyseparated at their point ends and arranged at such ends to be pressedinto contact, the insulating-block between the butt-ends of saidsections, and the head receiving such ends of the sections, meanswhereby the sections are secured in the head and the local circuithaving a battery and sounder and whose terminals are the plug-sections,the local circuit being arranged to be closed through the plug-sectionssubstantially as set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

WALLACE IRVING STOCKDON.

\Vitnesses:

JOHN 8. Low), BENJ.'F. CARMAN.

